Installation of loudspeakers in vehicles presents challenges, including adapting to space limitations and controlling echoes in installation cavities. Several types of speaker baffles have been developed but have various limitations. An automotive audio is a sound playing apparatus disposed to provide entertainment for a driver and a passenger during a trip. A loudspeaker, as a player element of the automotive audio, is usually mounted in an automotive door by using a baffle, and the baffle is covered by an interior trim panel on the door. However, there is a relatively big difference between thickness dimensions of existing automotive doors. Therefore, it is difficult for the baffle, used to help the loudspeaker be mounted in the door, to form a uniform standard size. In a conventional approach, the baffle is directly mounted in a mounting hole of the door. As a result, a case in which a size of a rear portion of the baffle is difficult to match in the door always occurs. If the size of the rear portion is relatively long, the acoustic relationship between the loudspeaker and the door may be affected. If the size of the rear portion is relatively short, the loudspeaker is not well protected. In addition, a front portion of the baffle also has a dimension thickness. If a size of the front portion is excessively long, a crossed reflex of sound between the loudspeaker and the door occurs, affecting the sound quality of play.